This invention relates to a waterproof seal for a connector that forms a watertight seal between a wire and a cavity in a connector housing.
In a waterproof connector, a rubber plug is used for preventing water from intruding into the interior of the connector through an insertion-side open end of a cavity for receiving a metal terminal. One conventional rubber plug is shown in FIG. 1. A rubber plug 101 includes a tubular rubber plug body 102 having lips 103 formed on an outer periphery thereof, and a tubular clamping portion 104 extending from one end of the rubber plug body 102. A wire 105 passes through both the rubber plug body 102 and the clampi/ng portion 104 in a closely-fitted manner. In this condition, a barrel 106 of a metal terminal is clamped to the clamping portion 104, thereby fixedly securing the rubber plug 101 to the metal terminal. When the rubber plug 101 is inserted, together with the metal terminal, into a cavity 107, the lips 103 on the outer periphery of the rubber plug body 102 are elastically deformed by the inner periphery of the cavity 107, and are held in intimate contact with the inner periphery, thereby preventing water from intruding into the area of contact between the inner periphery of the cavity 107 and the outer periphery of the rubber plug 101.
The rubber plug 101 is fitted in the cavity 107. When a bending force acts on the wire 105 extending outwardly from the open end of the cavity 107, the open end of the rubber plug 101 is deformed by a compressive force, applied from the wire 105, at an inner side of the bent portion, so that a gap G is formed between the wire 105 and the rubber plug 101 at an outer side of the bent portion, as shown in FIG. 2. When the gap G thus develops between the wire 105 and the rubber plug 101, water passes through the gap and reaches an inner portion of the cavity 107 where the metal terminal is received.
To deal with this problem, it has been proposed to provide a tubular portion extending from the outer open end of the rubber plug body, in which case the wire is passed through the tubular portion in closely-fitted relation thereto, so that a gap will not be formed at an outer side of a bent portion upon application of a bending force on the wire.
However, when the tubular portion is formed in this manner, a tension is applied from the wire to the rubber plug body through the tubular portion so that the rubber plug body may be elastically deformed at the outer side of the bent portion, thus forming a gap between the rubber plug body and the inner periphery of the cavity. Therefore, in this case, also, the waterproof function is adversely affected.
One example of the waterproof connector seal described above is shown in FIG. 3. A waterproof seal 1 includes a tubular body having a central bore 3 for passing a wire 2 therethrough, and has a mounting portion 4 adapted to be fixedly secured to an outer periphery of a sheath of the wire 2 at one of its ends by an insulation barrel of a metal terminal clamped to the mounting portion 4. A main waterproof sealing portion 5 having lips 6 formed on its outer peripheral surface is adapted to be fitted in a watertight manner into a cavity in a connector housing. Also provided is a thin, elongate wire-embracing portion 7 for embracing the outer periphery of the wire 2. The waterproof seal 1 is fixedly secured to the end portion of the wire 2, and is fitted in a cavity in the connector housing. If the wire 2 is bent in a head-nodding manner, the wire embracing portion 7, while kept in intimate contact with the wire 2, is deformed in accordance with the head-nodding motion to thereby prevent a bending force from acting on the main waterproof portion 5, thus preventing the main waterproof portion 5 from being deformed, so that a waterproof effect is maintained.
For passing the wire 2 through the waterproof seal 1 in order that the waterproof seal 1 can be fixedly secured to the end portion of the wire 2, the waterproof seal 1 is set in a jig, or is held by the hand, and then the wire 2 is inserted into the wire embracing portion 7 through its distal end. However, the wire embracing portion 7 of the waterproof seal 1 is thin over the entire length thereof. Therefore, if the front end of the wire 2 is caught by the distal end of the wire embracing portion 7 when the wire 2 is to be inserted into the wire embracing portion 7, the wire embracing portion 7 can easily buckle and deform so as to close the insertion port. Thus, a problem exists in that the insertion of the wire 2 is difficult.
Further, because the wire embracing portion 7 is thin throughout its length, it can be easily bent along any portion of its length. Accordingly, if the wire embracing portion 7 is bent in the vicinity of its distal end, a bending span is so short that the bending angle is large. As a result, the distal end of the wire embracing portion 7 is spaced apart from the wire 2, thereby forming a gap therebetween.